[sbo]

Hello,

I want to run two parallel reactions in OpenFoam and I use Arrhenius for both equations. Both reactions work seperately but they don't seem to influence one another as they should. Even the change in temperature doesn't seem to make a difference.
Does anyone have an idea why it doesn't work properly? Is Arrhenius not the right attempt?

Thanks,
sbo

[Kummi]

Hello sbo,
Do you got the solution for your question ? In my work, I'm facing the same issues now. In my case,

irreversibleSolidArrheniusHeterogeneousReaction
coal = 0.02627 H2O + 0.00296 CO2 + 0.012 C2H6 + 0.002 NH3 + 0.76 char
(1.3e13 25000 400 1.0) -- > EQU. (1)

irreversibleSolidArrheniusHeterogeneousReaction
coal = 0.06 CH4 + 0.76382 char
(1.3e13 42095 773 1.0) -- > EQU. (2)

When I try running with,
(i) only EQU. (1)
(ii) both EQUs. (1) and (2)
(iii) implementing EQU. (2) firstly followed by EQU. (1) [exchanging EQUs. thinking that only first EQU. being solved]
In (i) (ii) (iii), results are same.


When I solve only EQU. (2), results are different. So what I feel is, may be the influence of EQU. (1) dominates the other EQU. (2). But, still something fishy. Why there is not even a minor influence of EQU. (2) in the solution, although EQU. (1) dominates.

[dlahaye]

I suggest to find a reaction mechanism in Chemkin (or otherwise, possibly Cantera) for the combined reactions and use checkinToFoam to convert to format required for OpenFoam.

[Kummi]

Hello Mr. Domenico Lahaye,

Thank you for your comment. If I'm not wrong, in OpenFOAM chemkin is implemented only for gaseous reactions. In my case, its solid (coal) involved as a reactant.

I suggest to find a reaction mechanism in Chemkin (or otherwise, possibly Cantera) for the combined reactions and use checkinToFoam to convert to format required for OpenFoam.

So as per your thoughts, is that not possible to implement combined or multiple reactions in OpenFOAM unless we touch chemkin ?

Kindly share your thoughts.
Thank you

[dlahaye]

In my limited understanding, I distinguish two subproblems.

The first is defining the reaction mechanism. This is independent of gaseous or coal combustion.

The second is to perform combustion simulations using the reaction mechanism as input. Here indeed an appropriate solver is indeed required.

Hope this helps a bit.

Cheers, Domenico.

[Kummi]

Hello Mr. Domenico Lahaye,
Thank you for your thoughts.

elements 2(O N);
species 5(O O2 N2 N NO);
reactions
{
un-named-reaction-0
{
type reversibleArrheniusReaction;
reaction "NO^1 + N^1 = N2^1 + O^1";
A 2.1e+10;
beta 0;
Ta 0;
}
un-named-reaction-1
{
type reversibleArrheniusReaction;
reaction "N^1 + O2^1 = NO^1 + O^1";
A 5.83e+06;
beta 1.01;
Ta 3120;
}
}

I found such above multiple reactions when I gone through about ChemFOAM.
https://openfoamwiki.net/index.php/ChemFoam
I guess it should be the one, which I'm looking forward - where I found such settings in OF version 2.4.0 and higher versions. Currently, I'm using OF 2.1.1, the reason why I couldn't able to find such possibility before.
Let me try this and find the difference in results.

However when comparing OF versions 2.1.1 and 2.4.0, I couldn't able to find much differences in the code, concerning the above multiple reactions.. Any thoughts to share ?
Thank you again